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LIFE Chamber Chemical Equilibrium Simulations with Additive Hydrogen, Oxygen, and NitrogenJames A. DeMuth and Aaron J. SimonLawrence Livermore National Laboratory1. AbstractIn order to enable continuous operation of a Laser Inertial confinement Fusion Energy (LIFE)engine, the material (fill-gas and debris) in the fusion chamber must be carefully managed. Thechamber chemical equilibrium compositions for post-shot mixtures are evaluated to determinewhat compounds will be formed at temperatures 300-5000K. It is desired to know if carbon andor lead will deposit on the walls of the chamber, and if so: at what temperature, and whatelements can be added to prevent this from happening. The simulation was conducted usingthe chemical equilibrium solver Cantera with a Matlab front-end . Solutions were obtained byrunning equilibrations at constant temperature and constant specific volume over the specifiedrange of temperatures. It was found that if nothing is done, carbon will deposit on the wallsonce it cools to below 2138K, and lead below 838K. Three solutions to capture the carbon werefound: adding pure oxygen, hydrogen/nitrogen combo, and adding pure nitrogen. The best ofthese was the addition of oxygen which would readily form CO at around 4000K. To determinethe temperature at which carbon would deposit on the walls, temperature solutions toevaporation rate equations needed to be found. To determine how much carbon or any specieswas in the chamber at a given time, chamber flushing equations needed to be developed.Major concerns are deposition of carbon and/or oxygen on the tungsten walls forming tungstenoxides or tungsten carbide which could cause embrittlement and cause failure of the first wall.Further research is needed.This work performed under the auspices of the U.S. Department of Energy by LawrenceLivermore National Laboratory under Contract DE-AC52-07NA27344.2. IntroductionThe LIFE Chamber Chemical Equilibrium Study was performed to better understand thedifferent compounds that would form when a target of specified composition was ignited insidethe chamber at various temperatures ranging from 300 to 5000K. A chemical equilibrium solver,Cantera, was used to solve for the compound distributions inside the chamber. In equilibrationCantera minimizes the free energy of the system by distributing individual atoms among a pre-defined list of compounds at a specified temperature and specific volume. Specific heat datafits are taken from the NASA Thermo Tables and are used by Cantera to calculate Gibbs freeenergy for all the possible compounds.In the LIFE chamber, there will be an initial density of Xenon at 4- , into which am31hohlraum will be injected and ignited. The temperatures will reach levels of 5000K or higherinitially, but will immediately cool. As the components of the hohlraum cool they will begin toform compounds or condense/solidify onto the surrounding cooler walls of the system. Themain concern is that for a hohlraum made of Pb, C, Ta, N, O, H, D, and T, the Lead and theCarbon would condense or deposit respectively on the walls of the chamber. Tantalum could